1. Field of the Invention
The present invention concerns regulating integrated circuitry supply voltage, and more particularly concerns automatically dynamically controlling supply voltage responsive to performance of the integrated circuitry.
2. Related Art
Integrated high-speed chips are increasingly required to consume very low power. Such a difficult power-bandwidth tradeoff requires design techniques that make the most of each technology generation. Low-power design techniques are thus necessary to reduce power consumption. An effective power-reduction approach is to reduce the chip power supply. Given a certain power supply for a chip, and a need to selectively modify the supply voltage to certain circuitry, one well-known solution is to connect the chip""s power supply to an off-chip regulator and connect the voltage output of the regulator to the circuitry on the chip. However, system-level requirements increasingly demand that chips be fully integrated, resulting in so-called systems-on-a-chip (SOC""s). These system requirements tend to demand compatibility with standard technologies, but with no additional external power supplies. For example, it may be desirable for an SOC to operate from a single external power supply, but at the same time to operate a processor core on the SOC at a lower voltage than that which is supplied to the chip. This makes it difficult to integrate cores that work at lower voltages.
Besides selectively reducing voltage to reduce power consumption, it is also known to automatically raise regulator output voltage to compensate for performance degradation. However, conventional methods and structures for automatic control of voltage regulation tend to be complicated, so that the control circuitry consumes more power and takes up more area on the chip. Also, as in the above described voltage reduction applications, voltage boosting applications likewise generally use an off-chip, switching-type regulator. Moreover, these past arrangements also tend to require nonstandard technologies, such as bipolar transistors. See, for example, Gu-Yeon Wei and Mark Horowitz, xe2x80x9cA Fully Digital, Energy-Efficient, Adaptive Power-Supply Regulator,xe2x80x9d IEEE Journal of Solid-state Circuits, Vol. 34, No. 4 April, 1999, pages 520-528.
As indicated in the above brief explanation, a need exists for improvements in regulating integrated circuitry supply voltage for both selective voltage reduction and voltage boosting applications. This need is addressed in the present invention. According to an apparatus form of the invention, integrated circuitry on a single chip includes, a bit-programmable voltage regulator, circuitry for performing a processing function, and control circuitry operable to monitor an indication of performance of the circuitry and responsively output at least one control bit for controlling the regulator output voltage.
In an another aspect, the integrated circuitry is operable to receive an externally generated, time-based reference signal, and the integrated circuitry includes an on-chip oscillator for generating a time-based, oscillator output signal. The oscillator output signal varies in correspondence with the performance of the circuitry, which provides the above mentioned performance indication. The control circuitry receives the reference and oscillator output signals and generates the at least one control bit responsive to the two signals.
Objects, advantages, additional aspects and other forms of the invention will become apparent upon reading the following detailed description and upon reference to the accompanying drawings.